Caster direction-locking mechanism for mobile cart

ABSTRACT

A caster direction-locking mechanism for a mobile cart improves agility and stability of the cart during high speed movement. This cart includes four casters supporting it for rolling movement. Each caster has a wheel rotatable about a horizontal axis and is mounted with the cart for swiveling movement about a generally vertical axis. The caster direction-locking mechanism selectably locks two adjacent casters against such swiveling movement and with the horizontal axes thereof in generally mutually parallel relation. A handle is mounted on the cart for steering it and an actuator is associated with the handle for actuating the caster direction-locking mechanism to selectably lock and unlock the two casters against swiveling movement.

This application is a continuation of application Ser. No. 901,055 filedAug. 26, 1986, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a caster direction-locking mechanismfor a mobile cart, and more particularly to such a mechanism for amobile cart commonly called a "medical emergency crash cart" or simply a"crash cart", for medical emergency use in hospitals and other medicalinstitutions. The direction-locking caster mechanism in accordance withthe present invention provides the crash cart with improved high speedstability and maneuverability. A common safety latch mechanism forsimultaneously securing all compartments of the crash cart in a lockedcondition, indicating that the crash cart contains a full complement ofreadily accessible medical equipment may also be included.

2. Description of the Prior Art

A medical emergency crash cart commonly contains the medical equipment,instruments, and supplies that are necessary particularly for medicalprocedures practiced in cases of cardiac emergencies. However, the crashcart may be equipped for any type of medical emergency. The crash cartgenerally includes a housing having a plurality of drawers, shelves,and/or compartments for storing medical equipment and supplies such assyringes and drugs. The housing is supported by a plurality of wheels orcasters so that it may be moved rapidly from its place of storage to theplace of the medical emergency. To provide maximum efficiency during amedical emergency, a crash cart must therefore provide both (1) agileand stable mobility and (2) efficient storage with immediate visual andphysical accessibility to and organization of all medical equipment,instruments, and supplies.

One drawback of current crash carts is the loss of stability during highspeed travel. First, as a crash cart must be able to maneuver quickly insmall areas of patient's or hospital emergency rooms, it is desirable tosupport the housing on swivel casters. Second, as medical equipment,instruments, and supplies are expensive, each hospital maintains only alimited number of crash carts (e.g. one crash cart per floor orstation). Therefore, when a medical emergency occurs, a crash cartoperator must rush the cart through the hospital corridors often overrelatively long distances to the patient. However, swivel casters maycause the cart to be difficult to steer at high speeds particularly whenan attempt is made to change the direction of movement, for example, bygoing around corners in corridors or turning into the patient's room.Therefore, the crash cart operator must either reduce his speed throughthe halls or risk overturning the cart. The risk of overturningincreases when the operator must negotiate the cart around a corner, asswivel casters do not provide a firm pivot about which to turn butrather permit inertia of the cart to cause it to tend to continue tomove in its original direction. Alternatively, a crash cart may beoperated by two persons. However, this is less efficient and may in factnot be possible during any given emergency.

Another drawback of current crash carts is that they provide inefficientstorage and accessibility of medical emergency items. An importantcharacteristic of a crash cart is the physical accessibility of themedical equipment, instruments, and supplies stored in it. Immediateaccessibility to each item is desired when administering emergency care.In current crash carts, however, a "med tray" (containing syringes anddrugs such as ampules of adrenolin, and the like) is typically containedin a drawer within the cart. Storage of all supplies in drawers may makeadministration of care at the emergency scene difficult because accessmay only be had to one drawer at a time.

Still a further drawback of current crash carts is the limited abilityto visually inspect the medical equipment, instruments and supplieseasily and prior to an emergency. Generally, it is important that acrash cart always be fully equipped since if one or more items ismissing when an emergency occurs, medical professionals using the cartmay not be able to successfully treat the patient. However, for a numberof legitimate reasons, individual items are often taken in haste from acrash cart during non-emergency conditions. Each cart must therefore beperiodically inspected (e.g. each day or each shift) to insure that itis fully stocked. In light of the large number of items containedtherein, it is an inefficient use of hospital time and personnel tophysically inspect fully stocked crash carts. The ability to secure andto visually inspect a crash cart, to assure that a full complement ofthe critical instruments and supplies are contained therein, istherefore highly desirable.

For these and other reasons, the crash carts of the prior art are notentirely satisfactory. A need exists for an improved crash cart havinggreater high speed stability and maneuverability, greater accessibilityto the contents thereof, and a security system for maintaining andassuring maintenance of a full complement of medical equipment,instruments, and supplies therein.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to increase thestability and maneuverability of a crash cart when moving at highspeeds, particularly when maneuvering around corners, while retainingthe benefits of agility in close quarters.

It is another object of the present invention to improve theaccessibility of medical equipment, instruments, and supplies in amedical emergency crash cart.

It is yet another object of the present invention to provide a securitymechanism that offers easy visual inspection of at least most of thecritical contents of the crash cart and that assures that a fullcomplement of medical equipment, instruments, and supplies are storedwithin the crash cart.

These objects and further advantages are achieved by the presentinvention, which is an improved crash cart having means for locking atleast one of a plurality of swivel casters supporting the crash cart ina single direction of travel, a readily accessible med tray recessed inthe top surface of the cart, and a common security latch mechanism forsecuring all medical equipment, instrument, and supply compartmentsthereof.

More particularly, the crash cart of the present invention includes amechanism for locking two of four swivel casters, supporting a housingof the cart, for rolling movement in parallel planes with their axes ofrotation mutually parallel. Locking of these casters is quicklyaccomplished by manipulating a handle for steering the cart in thedirection of desired movement. When the lockable casters swivel to theirposition in the direction of desired movement they are automaticallylocked in place by the locking mechanism. Therefore, these lockedcasters can become pivots about which the cart can be turned when it isnecessary to change direction. Further, by second manipulation of thehandle, locking of the two casters can be quickly released so that allcasters can swivel and the cart can be easily manuevered into tightspaces.

The housing of the crash cart is molded with an integral med tray in itstop. The med tray is covered by a transparent cover providing easyvisual inspection of the tray's contents. Items stored in the tray arethose most frequently needed in an emergency. Therefore, the tray and atleast one drawer accessible from the front of the cart may besimultaneously opened such that the contents of both are simultaneouslyavailable. Storage areas on another side of the cart may also beaccessible at the same time. Other less frequently used supplies may bestored in more conventional drawers which are accessible from a side ofthe cart and which are also covered by a transparent panel.

The cover of the top med tray as well as drawers accessible from a sideof the cart and other essential supplies are all secured in lockedcondition by a common latching mechanism. A breakable seal provided onthe latching mechanism can provide quick visual confirmation that, ifunbroken, the complements of the cart are complete. The latchingmechanism is designed to easily shear the seal.

A more complete appreciation along with an understanding of otherobjects, features, and aspects of the present invention will becomeapparent from the following detailed description when considered inconjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a right-front perspective view of the preferred embodiment ofa crash cart in accordance with the present invention;

FIG. 2 is a left-rear perspective view of the preferred embodiment of acrash cart in accordance with the present invention;

FIG. 3 is a plan view, partially in cross-section and broken away toshow internal detail, of the top of the crash cart illustrated in FIGS.1 and 2 showing the common latching mechanism in locked condition;

FIG. 4 is a partial plan and broken away view similar to FIG. 3, of thecommon security latch mechanism of FIG. 3 in the unlocked condition;

FIG. 5 is a vertical cross-sectional view taken on plane 5--5 in FIG. 4of the security latch mechanism illustrated in FIGS. 3 and 4;

FIG. 6 is a vertical cross-sectional view taken on plane 6--6 in FIG. 5,showing further details of the latch mechanism;

FIGS. 7 and 8 respectively are a top plan and partially broken away viewand a vertical cross-sectional view of an alternative embodiment of aportion of the security latch mechanism;

FIGS. 9 and 10 respectively are a side view and a verticalcross-sectional view taken on plane 10--10 in FIG. 4 of I.V. solutioncompartments and a security latch mechanism therefor forming part of thecommon latch mechanism of the preferred embodiment;

FIG. 11 is a vertical cross-sectional view taken on plane 11--11 in FIG.4 illustrating an equipment drawer security latch mechanism forming partof the common latch mechanism of the preferred embodiment;

FIGS. 12 and 13 are respectively a front view and a verticalcross-sectional view taken on plane 13--13 in FIG. 12 of a disposablewaste container for the preferred embodiment of the present invention;

FIG. 14 is a vertical cross-sectional view taken on plane 14--14 in FIG.3 of a handle for steering the crash cart of the present invention andfor locking two swivel casters to provide directional stability for highspeed movement;

FIG. 15 is a view similar to FIG. 14 showing the handle in position tolock the casters;

FIG. 16 is a rear view of the caster direction-locking mechanism takenin the direction 16--16 of FIG. 15;

FIG. 17 is a view similar to FIG. 14 showing how movement of the handleis transmitted to unlock the two swivel casters; and

FIG. 18 is a horizontal cross-sectional view taken on plane 18--18 inFIG. 17 showing further details of the caster direction lockingmechanism.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawing, FIGS. 1 and 2 illustrate the preferredembodiment of the emergency medical crash cart of the present inventionin right-front and left-rear perspective views, respectively. The crashcart 10 includes a generally cubic housing 12 supported by four casters14 disposed near the lower four corners of the housing in order toprovide wide wheel bases in front to rear and side to side directions.For the purpose of description, the various sides of the crash cart willbe designated as follows: a front side 16 from which are accessible aplurality of I.V. solution compartments 17; a right side 18 from whichis seen a U-tube 20, an opening 22 in the housing 12, a door or backboard support bracket 24, a transparent cardiac back board 26 orremovable door supported at a bottom edge by the bracket 24, and asecurity latching mechanism locking plate 28; a rear side 30 having anoxygen tank compartment 32 and an operator's steering handle 34; and aleft side 36 comprising a front support tube 37, a rear support tube 38,a med tray cover hanger 40 and a disposable container 42 for refuse. Thetop of the crash cart comprises a recessed med tray compartment 44, amed tray compartment cover 46, a large recessed prep area 48, and asmall prep area 50. The bottom of the crash cart comprises an open-topequipment compartment 52, which depends from the housing 12 between thecasters 14 and is accessible from the opening 32 in the right side ofthe cart 10.

The crash cart 10 is generally composed of light-weight materials. Thehousing 12 may be composed of plastic, preferably a thermoplastic suchas polyethylene, and may be formed by a conventional process such asrotational molding. The U-tube 20 defines the opening 22 in the rightside 18 of the crash cart 10, and provides structural support therefor.The tube is therefore preferably composed of steel. The front and rearsupport tubes 37 and 38 on the left side 36 of the crash cart 10likewise provide structural support for the housing and are thereforealso preferably composed of steel tubing. The U-tube and support tubesare affixed to the housing by conventional means such as bolts or othersuitable structures. The placement of the other support tubes provides abroad wheel base for the cart to enhance its stability. The plastichousing 12 may further be molded to cooperate with the support tubegeometry, thereby increasing the structural rigidity of the crash cart.The med tray compartment cover 46, cardiac back board 26, and I.V.compartments 17 are preferably composed of a rigid transparent,translucent or tinted plastic to facilitate visual inspection of thetray 44 and the interiors of the housing 12.

FIG. 1 illustrates the crash cart in a secured, emergency-ready state.For purposes of illustrating the features of the cart, all medicalequipment, instruments and supplies normally present are not shown. Allcompartments of the crash cart are secured by a common security latchmechanism, to be described in detail below. The lock plate 28 is shownsecured by a breakable seal 54, indicating that all crash cartcompartments are secured, and have not been tampered with. Assuming thatthe cart was fully stocked when secured, a visual inspection of the seal54 therefore quickly assures hospital personnel that the crash cartcontains a full complement of medical emergency equipment, instruments,and supplies, avoiding unnecessary periodic physical inspections thatotherwise would require opening of all compartments of the cart.

FIGS. 1 and 2 illustrate further features of the present invention. Asshown in phantom lines in FIG. 1, a conventional telescoping I.V. stand56 may be mounted on the cart by inserting the stand into the rearsupport tube 38. The front support tube 37 may be similarly used, oralternatively used as a stand for holding a rotating platform (notshown), such as a difibrilator platform. When not used as described, thesupport tubes 37 and 38 may be capped with a plastic or rubber cap 58,as shown in FIG. 2.

FIG. 2 illustrates the crash cart 10 in an unsecurred state foremergency administration of treatment. The med tray compartment cover 46is normally supported by a lip 60 around the periphery of the med traycompartment 44, and is securely held thereon by a med tray compartmentcover security latch mechanism (to be described in detail below) incooperation with the med tray compartment cover hanger 40 as can be seenin FIG. 1. When the security latch mechanism is released, the med traycompartment cover 46 may be slid off the left side 36 of the cart 10beneath the med tray compartment cover hanger 40, dropped to that side,and hung on the hanger 40 by means of a hanger flange 62 secured to oneside of the cover 46. In this manner, the med tray compartment cover 46may be quickly and efficiently stored during medical emergencyadministration.

FIGS. 1 and 2 further illustrate the operator's steering handle 34 anddirectional locking caster mechanism (to be described in detail below)in an unlocked state. This mechanism in this state allows both the frontand rear casters 14 to swivel freely, providing maximum maneuverabilityin tight quarters.

FIG. 3 is a plan view of the top of the crash cart 10 illustrated inFIGS. 1 and 2, portions thereof having been cut-away to illustrate thecommon security latch mechanism, the operator's steering handle andcaster direction-locking mechanism, the oxygen tank compartment 32 and asupport 63 and a restraint 64, such as a buckle or Velcro strap, for anoxygen bottle, and a mount 66 for the disposable container 42.

The disposable container 42 is shown in detail in FIGS. 12 and 13 andincludes an elongate hollow body 69 made, for example, of inexpensiveplastic, having an open funnel-like mouth 71 at its top. A deformableshield 73 can be mounted at the mouth 75 of the funnel-like mouth 71 topermit entry of refuse thereinto but to prevent refuse from falling backout therefrom. The body 69 is also formed with two key-hole slots 77 inits front wall 79 for receiving the bolts 66 to removably mount thecontainers 42 on the housing 12.

The common security latch mechanism generally indicated at 68 comprisesa primary drawer security latch sub-mechanism 70, a med tray compartmentsecurity latch sub-mechanism 72, and an I.V. compartment security latchsub-mechanism 74. Each sub-mechanism is shown in a secured state,although for the purpose of illustrating the operation thereof, he medtray container cover is shown both in an unsecurred position (solidlines) and in a secured position (phantom lines).

In the common security latch sub-mechanism 68, the drawer security latchsub-mechanism 70 comprises a slide latch 76, a sleeve 78, and a seal tab80. The sleeve is transversely disposed between the sides 18 and 36 ofthe crash cart housing 12 and is affixed thereto by bracket and bolt orweld stud assemblies 82 and 84. The bracket and weld stud assembly 84affixing the sleeve to the left side 36 of the housing comprisesmounting bolts 86 which extend beyond the left side wall 88 of thehousing and thereby form the mount 66 for the disposable container 42.The bracket and weld stud assembly 82 affixing the sleeve to the rightside of the housing comprises studs 90 welded to the U-tube 20 and matedwith nuts 92 thereby, increasing the structural rigidity of the housing.

FIG. 11 shows the primary drawer security latch sub-mechanism 70 inpartial vertical cross-sectional view. The slide latch 76 comprises aslide member 94 having antifriction feet 96 made of, for example, nylonso that the slide member 94 can easily slide within the interior of thesleeve 78. The slide latch 76 further comprises the locking plate 28,which is hinged by a hinge pin 95 to one end of the slide member 94.During a secured emergency-ready state, the slide member 94 extends pastthe right extreme of the sleeve and through a small opening 98 in theright side 18 of the housing. The locking plate 28, therefore, can hangfrom the hinge pin 95 over the seal tab 80. The tab 80 is affixed bybolting to the bottom of the sleeve 78 and extends through the rightside of the housing. The locking plate 28 is provided with a shearingslot 100 (FIG. 1) which fits over and closely conforms to thecross-sectional shape of the seal tab 80 when in the securedemergency-ready state. The seal 54, which may be plastic, is insertedthrough a hole 102 in the seal tab 80 to maintain the locking plate 28in the secured position. In the secured emergency-ready state, thecardiac backboard or door 26 is supported by the support bracket 24disposed at the bottom of the opening 22 on the right side 18 of thehousing 12 and is held in the upright position shown in FIG. 11 by thelocking plate 28. The cardiac backboard therefore rests between drawers104 mounted inside the housing 12 and the locking plate 28, securing thedrawers 104 and the open top equipment compartment 52 disposed at thebottom of the housing 1 in closed condition.

Referring again to FIG. 3, the med tray compartment security latchsub-mechanism 72 is coupled to the primary drawer sub-mechanism by apositioning rod 106 and position pins 108. The position pins 108 areaffixed to the slide member 94 and extend upwardly through an opening110 in the sleeve 78. A section of the positioning rod 106 having a jog109 therein is disposed between the positioning pins and another section111 of the rod 106 is linked to a cover locking bracket 112 of the medtray compartment security latch sub-mechanism 72.

FIGS. 4 and 5 illustrate the common security latch mechanism 68 of FIG.3 in the unsecured emergency-application state. In FIG. 4, the lockingplate 28 has been lifted to vertical position, thereby shearing the seal54, and has been translated into the sleeve thereby translating theslide member 94 toward the left side 36 of the housing 12. Thepositioning pins 108 thus have translated toward the left side causingthe jog 109 in the section 107 of the rod 106 thereby to be translatedtoward the front side 16 of the housing. The cover locking bracket 112coupled to the section 111 of the rod 106 is thus drawn in the directionof the front side of the housing. As shown in FIG. 5, the cover lockingbracket 112 is provided with front and rear bracket guide slots 118 and120 which accommodate respective bracket guides 122 and 124, the guide122 being formed by one of the bolts holding the sleeve support bracket82. The front bracket guide slot 118 extends in a horizontal plane.However, the rear bracket guide slot 120 is inclined. Therefore, as thecover locking bracket 112 translates toward the front side 16 of thehousing 12, it also translates in a downward fashion due to interactionof rear guide 124 and the inclined rear bracket guide slot 120. In thismanner, a med tray cover lock pin 126 secured approximately in thecenter of the locking bracket 112 is withdrawn from a hook 128 of themed tray compartment cover 46 as clearly shown by phantom and solidlines in FIGS. 3 and 5. FIG. 6 shows the med tray compartment cover inthe secured position. The hook 128 of the med tray compartment coverextends through an opening 130 in the tray wall 132 into a cavity 134therein and the med tray cover locking pin affixed to the cover lockingbracket 112 is inserted into the hook thereby securing the med traycompartment cover in a closed state when the locking bracket 112 ismoved toward the rear 30 of the housing and upwardly by reverse movementof the slide member 94.

FIGS. 7 and 8 illustrate an alternative embodiment of the med traycompartment security mechanism. In this embodiment, the hook 128'affixed to the med tray compartment cover is segmented, having a gap 129for accommodating a med tray cover locking pin 126'. In this manner, thecover locking bracket needs only to be translated in a horizontal plane,as shown in FIG. 8. The rear bracket guide slot 120' is therefore cuthorizontally, such that the bracket translates horizontally on theforward and rear bracket guides 122' and 124'. In other respects the medtray compartment security mechanism is the same as that previouslydescribed.

Referring now to FIG. 3, 4, 9, and 10, the I.V. compartment securitylatch sub-mechanism 74 includes a pivot rod 136 pivotable about avertical shaft 138. As see in FIG. 9, the vertical shaft 138 is mountedfor pivoted movement on a lower mounting bracket 151 and an uppermounting bracket 154 secured to the front of the housing. A second pairof positioning pins 140 is affixed to the slide member 94 and the rod136 projects therebetween. When the primary drawer security latchsub-mechanism 70 is operated, i.e., when the slide member 94 slides totoward the left side 36 of the housing 12, the rod 136 and shaft arerotated in the counter clockwise direction as seen in FIGS. 3 and 4.

As best seen in FIG. 10, each I.V. compartment 74 comprises a structurehaving front and bottom walls 141 and 142 joined at an apex 144. Eachstructure is pivoted within a recess 146 formed in the front side 16 ofthe housing 12 of the crash cart, on pivot pins 148. Each I.V.compartment also has a pair of side walls 150 on which the respectivepivot pins 148 are mounted. Stops 152 are mounted on the interior sidewalls 153 of the recess 146 to abut the side wall 150 when a compartment74 is in the open position (phantom lines in FIG. 10) and to abut thefront wall 140 when a compartment is in the closed position (solid linesin FIG. 10). In the open positions of each compartment, the front wall140 is held at an angle inclined downwardly toward the housing so thatan I.V. container does not fall therefrom.

A number, equal to the number of I.V. compartments 74, of lock tabs 156are secured, for example, by welding, to project radially from thevertical shaft 138 through mating holes 139 in the front side of thehousing. In the locked position shown in FIGS. 3 and 10, these lock tabsoverlie the bottom wall 142 of each I.V. compartment to hold each I.V.compartment in its closed position. However, when the primary drawersecurity latch sub-mechanism 70 is moved to its open position asdescribed above, the pivot rod 136 is rotated in the counter-clockwisedirection (as seen in FIGS. 3 and 4) causing the vertical shaft 138 andlock tabs 156 also to rotate in the counter-clockwise direction therebyfreeing each I.V. compartment for pivoted movement as described above.In this way, access to the contents of each I.V. compartment isprovided.

Of course, to lock the I.V. compartments, they all are first closed andthe primary drawer security latch sub-mechanism 70 is then drawn to itsforward position moving the slide member 94 toward the right side 18 ofthe crash cart 10, in turn rotating the rod 136, vertical shaft 138, andlock tabs 156 in a clockwise direction such that the lock tabs overliethe extreme of each second wall 142 of the I.V. compartments.

The caster direction-locking mechanism for locking and unlocking the tworearmost swivel casters 14A and 14B of the crash cart 10 of the presentinvention will now be described with reference to FIGS. 14 through 18.

As can be seen there, the rearmost swivel casters 14A and 14B arerespectively secured for swiveling movement in the rearmost leg of theU-tube 20 and the rear support tube 38. Each caster includes a shaft(not shown), extending into and secured in the respective support tube,and is supported by a bearing (not shown) that permits swivellingmovement. The caster further includes a generally U-shaped horn 158having a base 159 from which the unshown shaft projects and having ahorizontal axle 160 spanning the legs 162 of the horn at a positionvertically offset from the axis of the supporting tube. A wheel 164 issupported for rotational movement on each axle 160.

The caster direction-locking mechanism includes the operator's handle34, which may be rotationally or blow molded, for example, and which ismounted for pivoted movement on a horizontally extending hollow shaft166 rotatably secured in a recess 168 in the rear side 36 of the housing12. The handle 34 includes an arm 169 projecting from the shaft 166 anda pair of grips 171 (FIG. 2) that can be manipulated by an operator. Ahandle lock release bar 170 is mounted for reciprocal movement withinthe handle and includes a pair of legs 172 that pass through the shaft166 in a direction perpendicular to the axis of the shaft. The extremesof the legs 172 constitute handle locking pins 174 that project throughan abutment plate 175 secured to the handle 34 in the region of theshaft 166. A retainer pin 176 passes through each leg 172 of the handlelock release bar 170 and a biasing spring 178 is compressed between theretainer pin and a confronting surface 180 of the handle. Thus, as isapparent from FIGS. 14 and 15, the biasing springs 178 urge the handlelocking pins 174 to their projected positions. Similarly, the portion179 of the bar spanning the legs 172 can be pulled to withdraw the pins174 against urging of the springs 178.

A handle locking bracket 182 is secured to the inner wall 184 of therecess 168 in the rear side 36 of the housing. This bracket includes anextension 186 that is inclined downwardly at an acute angle from thatportion of the bracket 182 secured to the housing. A pair of lockingholes 188 is formed in the extension and each registers with the handlelocking pins 174. Thus, as can be seen from a comparison of FIGS. 14 and15, the handle may be rotated in a counter clockwise direction from itsdepending or caster unlocking position (FIG. 14) to an upstanding orcaster locking position (FIG. 15) during which the handle locking pins174 engage the extension 186 of the handle locking bracket 182. Thisengagement urges the locking pins 174 and hence the handle lock releasebar 170 to move in a direction opposite that urged by the biasingsprings 178. When the pins 174 are registered with the locking holes 188of the extension 186, the force exerted by the biasing springs 178causes the pins and handle release bar to return to their rest positionwith the pins projecting into the holes. Thus, the handle is locked inits upright position.

The handle may be released from the locked position by pulling theportion 179 against the force of the biasing springs to withdraw thelocking pins 174 from the holes 188 and thereafter by rotating thehandle in a clockwise direction as seen in the figures again to itsretracted position.

Referring now to FIG. 17, it will be seen that the shaft 166 has a cam190 attached to it. This cam is positioned to engage a lifter bracket192 that is mounted for pivoted movement about a pivot pin 194 securedin the interior of the crash cart housing 12. When so engaged, and asseen in FIG. 17, the lifter bracket is rotated in a clockwise directionto urge the free end therof upwardly.

The lifter bracket is coupled to a lifter rod 196 that is guided throughan opening 198 formed in an inclined section 200 of the rear wall of thehousing. The extreme of the lifter rod opposite that coupled to thelifter bracket is connected to one end of a coupling rod 202 mounted forpivoted movement at the bottom of the housing in a pair of pivotbrackets 204, as seen in FIG. 18. Thus, when the lifter rod is lifted byinteraction of the cam 190 and the lifter bracket 192, the coupling rod202 is rotated in a clockwise direction as seen in FIG. 17.

Each extreme of the coupling rod is formed with a jog 206 and anextension 208 that mates with an enlarged aperture 215 in a D-shapedcollar support lever 210 as shown in FIGS. 14, 15 and 18. Each supportlever 210 is mounted for pivoted movement about a pivot pin 212 securedto the housing of the crash cart. A coil spring 220 is carried on eachpivot pin 212 as shown in FIG. 18 and is arranged to urge the free endof each support lever downwardly. It will be appreciated that when thelifter rod 196 is lifted as described above, the coupling rod will berotated in the clockwise direction also to rotate the support levers 210in a clockwise direction.

Each support lever carries a D-shaped collar at its free end. EachD-shaped collar 214 encircles one of the support tubes at the rear ofthe crash cart just above the horn 158 of the associated caster.

The flat side 216 of each D-shaped collar 214 is formed with acaster-locking notch 218 as shown clearly in FIG. 16.

When the handle 34 is in its steering position shown in FIG. 15, the cam190 is disengaged from the lifter bracket 192. Accordingly, the supportlevers 210 are permitted to rotate under the influence of gravity andthe coil springs 220 in a counter-clockwise direction as seen in FIG. 17thereby permitting the D-shaped collars first to ride on the base 159 ofeach horn of each rear caster. However, when each rear caster reaches aposition shown in FIGS. 15 and 16, again under the influence of gravitythe D-shaped collars will rotate further in the counter-clockwisedirection permitting the notches 218 to engage and embrace the sidesurfaces of the legs 162 of the horns 158 thereof. In this way, each ofthe wheels of the rear casters will be locked in parallel planes in thedirection of movement of the crash cart i.e. with their respective axels160 in mutually parallel relation. These locked casters can then serveas pivots to aid high speed maneuverability of the cart 1. However, whenthe handle is returned to its retracted position shown in FIG. 14, thecam 190 engages the lifter bracket 192 to lift the support levers 210and attached D-shaped collars 214 thereby disengaging the notches fromembrace of the horns of the rear casters. Accordingly, these rearcasters are again permitted to swivel freely to permit easymaneuverability of the crash cart in tight spaces.

It will also be appreciated that the respective caster lockingmechanisms on the casters 14A and 14B independently operate to lock theassociated caster in the particular position when that position isassumed. Of course, the respective particular positions of the casters14A and 14B may not be assumed at the same time. However, both lockingmechanisms are released from locked condition at the same time byoperation of the handle.

It will be readily seen from the description set forth above that thecrash cart of the present invention provides many advantages whichinclude the following:

1. Easy visual confirmation that the crash cart has a full complement ofcritical equipment and supplies.

2. Easy access to all compartments of the crash cart which arenevertheless securely sealed simultaneously in an emergency-readycondition by a locking mechanism operable by a single locking plate.

3. Provision of a simple, easily operated mechanism for locking the tworear swivel casters of the cart for relation in the single direction ofmovement of the cart so that the cart may be quickly and easilymaneuvered but further provision of easy release of these swivel castersfor easy maneuverability in tight spaces.

Although specific embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis for purposes of understanding. Modification of the preferredembodiments described herein may be made by those skilled in the artwithout departing from the scope of the present invention which is setforth in the following claims.

What is claimed is:
 1. A cart having a first end and a second end, saidcart comprising:at least three casters supporting said cart for rollingmovement, a first two of said casters being adjacent each other andsupporting said cart in the region of said first end, and at least oneother of said casters supporting said cart in the region of said secondend, each said caster including a wheel rotatable about a horizontalaxis and being mounted with said cart for swiveling movement about agenerally vertical axis; first locking means selectably operable to lockone of said first two casters against said swiveling movement when saidone of first two caster swivels to a first predetermined positionrelative to said first end of said cart; second locking means selectablyoperable, independently of locking of said one caster by said firstlocking means, to lock the second of said first two casters againstswiveling movement when said second caster swivels to a secondpredetermined position relative to said first end of said cart, with thehorizontal axes of said first two casters in generally mutuallyparallel, substantially collinear relation; means for interconnectingand simultaneously enabling said first locking means and said secondlocking means independently to lock said one caster and said secondcaster when they respectively swivel to said first predeterminedposition and to said second predetermined position; handle means, forsteering said cart, mounted at said first end; and actuator meansassociated with said handle means for actuating said interconnecting andenabling means thereby operating said first locking means and saidsecond locking means to selectably lock and unlock said one and saidsecond of said first two casters against said swiveling movement.
 2. Acart according to claim 1, wherein each of said one and said second ofsaid first two casters comprises an inverted, generally U-shaped hornhaving a base and a pair of legs depending from said base, saidhorizontal axis of each of said one and said second of said first twocasters spanning the distance between said legs thereof and saidvertical axis projecting upwardly from said base thereof, and whereinsaid first and said second locking locking means each comprises means,associated with the respective one and the second of said first twocasters, for embracing said horn of said associated caster when saidassociated caster assumes said first predetermined position or saidsecond predetermined position respectively.
 3. A cart according to claim1, wherein said first and said second locking means each comprises:acollar encircling said vertical axis of said associated caster andhaving one wall formed with a notch therein having lateral dimensionlarger than the distance between the outer surfaces of said legs of saidhorn of said associated caster; and wherein said interconnecting andenabling means comprises means for mounting each said collar formovement among a first position suspended above said horn of saidassociated caster, a second position resting on the upper surface ofsaid base of said horn of said associated caster, and a third positionwith said notch embracing said horn of said associated caster when saidassociated caster assumes said first predetermined position or saidsecond predetermined position respectively.
 4. A cart according to claim3, wherein said mounting means comprises a lever for each of saidcollars, mounted for pivoted movement at one end about a pivot axisfixed relative to said associated caster, with an associated collarbeing mounted in the region of the free end thereof opposite said oneend.
 5. A cart according to claim 4, wherein said actuator meanscomprises a lifter rod linking said levers to said handle.
 6. A cartaccording to claim 4, wherein said handle comprises:a shaft mounted forrotary movement; an arm projecting from said shaft for effecting rotarymovement thereof between caster locking and unlocking positions; and acam mounted on said shaft; and wherein said actuator means comprises: alifter bracket mounted for pivoted movement about a pivot point at oneend thereof and having a free end positioned to be engaged by said cam;and lifter rod linking said free end of said lifter bracket and saidfree end of at least one of said mounting means levers; said cam beingarranged to engage said lifter bracket when said handle is in saidcaster unlocking position to move said mounting means lever and therebymove said collar to said first position thereof.
 7. A cart according toclaim 6, further comprising coupling rod means for coupling saidmounting means levers together and thereby for transmitting movement ofsaid lifter rod to both said mounting means levers.
 8. A cart accordingto claim 6, further comprising means for securing said arm of saidhandle in said caster locking position.
 9. A cart according to claim 8,wherein said securing means comprises:at least one handle locking pinprojecting through said shaft, means for urging said locking pin to aprojected position protruding from said shaft; and means associated withsaid cart defining a handle locking hole for receiving said locking pinwhen said arm of said handle is moved to said caster locking position.10. A cart according to claim 9, further comprising means for guidingsaid locking pin into registry with said handle locking hole.
 11. A cartaccording to claim 9, further comprising manually manipulable means formoving said locking pin, against urging by said urging means, away fromthe projected position thereof.
 12. A cart according to claim 1, furthercomprising means for urging said first and said second locking means toposition to lock said one and said other of said casters respectively.13. A cart comprising:A. four casters supporting said cart for rollingmovement, each said caster including a wheel rotatable about ahorizontal axis and being mounted with said cart for swiveling movementabout a generally vertical axis; B. means for selectably locking twoadjacent casters against said swiveling movement and with the horizontalaxes thereof in generally mutually parallel relation (1) each of saidtwo adjacent casters comprising an inverted, generally U-shaped hornhaving a base and a pair of legs depending from said base, saidhorizontal axis spanning the distance between said legs and saidvertical axis projecting upwardly from said base, and (2) said lockingmeans comprising means, associated with each of said two adjacentcasters, for embracing said horn of said associated caster when saidassociated caster assumes a particular position (a) said embracing meanscomprising a collar encircling said vertical axis of each of said twocasters and having one wall formed with a notch therein having lateraldimension larger than the distance between the outer surfaces of saidlegs of said horn of said associated caster; and (b) means for mountingeach said collar for movement among a first position suspended abovesaid horn of said associated caster, a second position resting on theupper surface of said base of said horn of said associated caster, and athird position with said notch embracing said horn of said associatedcaster when said one caster assumes the particular position, saidmounting means comprising a lever for each of said collars, mounted forpivoted movement at one end about a pivot axis fixed relative to saidassociated caster, with an associated collar being mounted in the regionof the free end thereof opposite said one end; C. handle means forsteering said cart comprising:(1) a shaft mounted for rotary movement;(2) an arm projecting from said shaft for effecting rotary movementthereof between caster locking and unlocking positions; and D. actuatormeans associated with said handle means for actuating said casterlocking means to selectably lock and unlock said two casters againstsaid swiveling movement, said actuator comprising:(1) a lifter bracketmounted for pivoted movement about a pivot point at one end thereof andhaving a free end positioned to be engaged by said cam; and (2) a lifterrod linking said free end of said lifter bracket and said free end of atleast one of said mounting means levers; (3) a said cam being arrangedto engage said lifter bracket when said handle is in said casterunlocking position to move said mounting means lever and thereby movesaid collar to said first position thereof.
 14. A cart according toclaim 13, wherein said actuator means comprises a lifter rod linkingsaid levers to said handle.
 15. A cart according to claim 13, furthercomprising coupling rod means for coupling said mounting means leverstogether and thereby for transmitting movement of said lifter rod toboth said mounting means levers.
 16. A cart according to claim 13,further comprising means for securing said arm of said handle in saidcaster locking position.
 17. A cart according to claim 16, wherein saidsecuring means comprises:at least one handle locking pin projectingthrough said shaft, means for urging said locking pin to a projectedposition protruding from said shaft; and means associated with said cartdefining a handle locking hole for receiving said locking pin when saidarm of said handle is moved to said caster locking position.
 18. A cartaccording to claim 17, further comprising means for guiding said lockingpin into registry with said handle locking hole.
 19. A cart according toclaim 17, further comprising manually manipulable means for moving saidlocking pin, against urging by said urging means, away from theprojected position thereof.
 20. A cart according to claim 13, furthercomprising means for urging said caster locking means to position tolock said casters.
 21. A cart according to claim 13, wherein said casterlocking means is operative to lock each one of said two castersindependently of locking the other of said two casters.